Air filtration systems are used in many situations to purge unwanted substances from the air. Such air filtration systems generally exist in a variety of forms, depending upon their use and function.
One type of air filtration system is the ductless fumehood. Ductless fumehoods provide a protected enclosure for isolating a workspace from an ambient atmosphere, in order that dangerous substances may be handled safely in the workspace without endangering nearby personnel and the surrounding environment.
More particularly, and looking now at FIG. 1, there is shown a typical prior art ductless fumehood 5. Ductless fumehood 5 generally comprises an enclosed workspace 10 accessed by a front door 15, with front door 15 engaging a sash 20 when the enclosed workspace is “sealed”. An air inlet 25 admits ambient air into enclosed workspace 10, and an air outlet 30 removes air from enclosed workspace 10. Air from air outlet 30 is passed through a filter 35 before being released to the ambient air (e.g., the room air within a laboratory). Filter 35 removes hazardous substances from the air, thereby rendering the air safe before it is vented to the ambient air. An outlet fan 40 is generally provided at air outlet 30 so as to keep enclosed workspace 10 at a negative pressure differential relative to the ambient air, in order to ensure that any air within the enclosed workspace passes through filter 35 before being vented to the ambient air. A sensor 45 is generally provided at the outlet of filter 35 so as to ensure that the filter purges any hazardous substances from the workspace air before that air is then vented to the ambient air. Outlet fan 40 and sensor 45 are generally connected to an alarm 50 which can alert the operator in the event that outlet fan 40 and/or sensor 45 fail.
Ductless fumehoods have become popular due to their technical effectiveness, low acquisition and implementation costs, rapid installation, and substantial energy savings. More particularly, with proper filter selection, ductless fumehoods can be extremely effective in removing hazardous materials from the air. Furthermore, due to their simple design and their ductless nature, ductless fumehoods are relatively inexpensive to buy and relatively inexpensive to implement, since they do not require the extensive engineering and installation efforts normally associated with ducted fumehoods. Furthermore, installation is very fast, since ductless fumehoods require little more than uncrating and initial setup and testing before use. Ductless fumehoods are also quite energy efficient, since they return the filtered air to the room rather than venting it to the outside atmosphere. As a result, already-heated air is retained in the room during winter and already-cooled air is retained in the room during summer.
Despite the significant advantages associated with ductless fumehoods, current ductless fumehoods have nonetheless encountered certain resistance in the marketplace. This is generally due to concerns about the risk of failure in the filtration system. More particularly, while conventional ductless fumehoods generally have their outlet fan 40 and sensor 45 connected to an alarm 50 which can alert the operator if outlet fan 40 and/or sensor 45 should fail, they still require that the operator be in the general vicinity of the ductless fumehood and that the operator be somewhat attentive. This can be of concern when the ductless fumehood is located in a loud and/or otherwise distracting environment, and/or when placed in the hands of poorly trained and/or unreliable personnel. Furthermore, this can present an administrative problem when the ductless fumehoods are deployed in large numbers and dispersed throughout several laboratories. Due to these concerns and inconveniences, some safety organizations have advised against the use of ductless fumehoods even though ductless fumehoods can offer significant advantages in the areas of technical effectiveness, low acquisition and implementation costs, rapid installation, and substantial energy savings.
In addition to the foregoing, current ductless fumehoods are not modular. As a result, when a new fumehood model with a different filter capacity must be produced, manufacturers must fabricate a new filtration system and all of its command and control elements. Thus, manufacturers must provide filtration systems in a variety of capacities and dimensions, which multiplies both the number of different fumehood models which must be manufactured as well as their associated manufacturing costs. Furthermore, the administrative burden associated with managing a large number of these ductless fumehoods can be enormous. As an illustration of this problem, consider the example of trains without cars, made up only of locomotives, with each locomotive having a different seating capacity. The cost of manufacturing large numbers of different models, and the administrative burdens associated with managing a fleet of such trains, made up of countless different models, can be prohibitive. The situation is currently somewhat analogous for the manufacturers and users of conventional ductless fumehoods.